How to Repair Damaged Wood Trusses
With care and attention, you can repair damaged wood trusses without having to disassemble your home's roof supports. Follow these steps below to fix damaged wood trusses that happen during the initial construction phase.
Step 1: Determine the Location of Damage
Wood trusses can be damaged by splitting and cracking if other wood trusses are dropped or thrown on top of them. The connector plates can lose teeth or pull out of the wood completely. Twisting from too much torque can warp the wood trusses, necessitating redesign and replacement.
Step 2: Choose the Correct Method to Repair Damage
Damage repair methods can involve repairing trusses with wood adhesives, replacing fasteners with similar new ones or with a different type, and installing lumber scabs or gussets to absorb additional stress.
Step 3: Repair the Wood Truss
Where a small split or crack has occurred in the wood truss, seal the crack or split with wood adhesive, and clamp the repair for 24 hours. Test the truss before applying additional stress. If the repair holds, install the truss. If the repair is flawed, add a wood scab or a gusset to the wood truss to ensure it can tolerate the stress required. Fasten the scab or gusset with self tapping nails or screws.
Step 4: Repair or Replace a Connector Plate
Remove the damaged connector plate, and replace it even if it is only missing a few teeth. Refill the holes in the wood truss with wood adhesive and apply a wood scab to patch it. Let the repaired wood truss set for 24 hours in dry conditions to secure the repair. Apply connector plate at a 1/8 inch spacing from the original plate installation, so that most of the plate is gripping fresh wood. Use a connector plate press to make the most secure connection between the plate and the truss. Do not insert the repaired truss into the construction framework until the adhesive has completely set, forming a snug, squeak-free bond.
Step 5: Apply Gussets to Both Sides of the Wood Truss
Apply OSB or plywood gussets to both sides of a wood truss. Clamp the gussets to the truss while nailing. Drive the nail through the front face gusset, through the truss and through the rear face gusset. Bend the nail tip over and sink it into the gusset to create a firm hold. Drive a second nail through all 3 layers starting from the rear face, and bend it at the tip into the gusset for a double shear hold. Every 10 nails put into the gussets, in double shear, will result in a holding strength of 1000 pounds.
Step 6: Choose Optimum Conditions for Repairs
Ensure the wood trusses, connector plates and all fasteners are clean, dry, and free from rust, mud or other contaminants. Do repairs out of the weather where possible, or in dry sunny conditions. If rain is in the forecast, move repaired trusses under a tarp to reduce swelling from moisture.